* src/metalink.c (retrieve_from_metalink): If opt.trustservernames is
true, use the basename of the metaurl's name to save the xml file
* doc/metalink-standard.txt: Update doc. With --trust-server-names any
Metalink/HTTP Link application/metalink4+xml file is saved using the
basename of the "name" field, if any. Update Metalink/HTTP examples
* testenv/Makefile.am: Add new file
* testenv/Test-metalink-http-xml-trust-name.py: New file. Metalink/HTTP
automated Metalink/XML, save xml files using the "name" field tests
